Electric heating device



Feb. 11, 1964 BENED|KT 3,121,157

ELECTRIC HEATING DEVICE Filed Aug. 22, 1961 '4 m, 'w' I; I O I 9/ I ID '4 I ll' l" 3 11 A h INVENTOR:

JULIO BE Em KT,

HIS ATTORNEY.

i United States Patent 3,121,157 ELECTRIC HEATING DEVICE Julio Benedikt, 0.R.O. 3089, Buenos Aires, Argentina Filed Aug. 22, 1961, Ser. No. 133,204 1 Claim. (Cl. 219-40) This invention refers to an electric heating device, and

' more particularly to such a heater provided with thermostatic self-control means permitting it to maintain a constant temperature in spite of being permanently connected to a power supply.

Various elements and devices used for heating purposes are already known, and are being utilized in households. The simplest and cheapest of such devices include rubber bottles or bags which have to be filled with hot water and supply the heat stored by the liquid until cold. In order to make the heat last longer, the known foot-warmers have been developed, comprising a suitably insulated electric resistance enclosed in a container and surrounded by a diffusing medium capable of absorbing and diffusing the heat developed by the resistance. At best, this medium is a refractory powder but in most cases it simply sand. Experience has shown that such devices have many drawbacks since the electric resistance frequently burns out, the devices have a certain unpleasant smell and frequently also get excessively heated up. Furthermore, since the heat radiated by the resistance has to pass through a heterogeneous diffusing medium composed of the insulation generally made of mica or asbestos and the diffusing material which consists of sand or refractory powder, the heat transmission is too slow requiring a higher consumption of electricity and resulting in increased operating costs.

Other known devices include electric pillows and blankets which consist of a length of heating wire arranged between two layers of textile material. In order to 'avoid overheating which could set on fire the blanket or pillow, these devices are provided with thermostats capable of interrupting the current flow when the temperature reaches a predetermined value. These devices may be utilized for keeping them permanently connected with the mains. It will be appreciated that in View of the nature of the component pants of these devices their cost is usually rather high.

For these reasons the present novel heating device has been designed; the same uses for the first time as far (as we know, for the purpose of domes-tic heating, the heat developed by ionic transfer. The invention comprises a sealed container, preferably made of heat-conducting material, partially filled with an electrolyte comprising a salt solution at a concentration of over 6% by weight and inside of which the electric current conducting electrodes are arranged. The container has a flexible cover to close its mouth, in which the connecting pins of a plug are firmly inserted. The ends of these pins project on the inside of the cover and rest on the terminals of the electrodes which are fixed in said mouth. This means to say that the connection is made by more contact and by virmo of the elastic strain of the cover. In the space between both electrodes, in said connecting zone, there is a small deflated bulb or bag communicating with the interior of the container. When the heat developed expands sufficiently the air inside the container or develops the necessary amount of steam, said bulb or bag inflates and presses against the elastic cover until the deformation of the latter causes the disengagement of the ends of said pins from said electrodes, interrupting the electric connection to the power supply.

The main advantages of the device reside in the fact that the electrodes are not exposed to any effects of overheating but on the contrary always receive a relatively 3,121,157 Patented Feb. 11, 1964 ice gentle and uniform heat. The device never will be overheated since the temperature limit is always determined by the boiling point of the liquid it contains. As this liquid is confined in a sealed space, not being allowed to escape, the amount of heat supplied will be absorbed by the liquid in the form of latent heat and therefore the temperature will be maintained at a constant level as long as some portion of liquid remains in the container. Although the device may inadvertently remain plugged in for any length of time and even permanently, the temperature will not rise continuously but will be stabilized at around (3., namely the boiling point of the liquid, because the heat supplied would spend itself by evaporating the liquid, but as this vaporization occurs in. a closed cycle a thermodynamic equilibrium is reached through the continuous condensation of the steam produced. On the other hand, excessive heating operates the aforementioned interrupting device.

In order to understand the invention and the way of putting it into pnactice reference may be had to the annexed drawing showing an embodiment of the invention by Way of illustration only and not limiting the same in any way whatever; in said drawing:

FIG. 1 is a plan view, partly in longitudinal section, of the heating device the container of which is illustrated as a rubber bag with a portion removed in order to show the arrangement of the various members forming the device;

FIG. 2 is a fragmentary large scale sectional view of the device breaking the electric connection, and shows how the same operates under the steam pressure developed by the heat.

In said figures like reference characters indicate like or corresponding part-s.

Referring now to the dnawing, 1 indicates the container of the device which in the example shown is completely similar to the known hot water bottles. The container holds its interior 2 an electrolyte that is composed of a sodium chloride solution at a concentration exceeding 6% by weight as experience has shown that this concentration secures optimum ionic transfer in the least time possible. The device provided with this electrolyte operates on alternating electric current. Should instead direct current be used a depolarizer should be added to the electrolyte in order to avoid the dissociation of the water in its components oxygen and hydrogen. Inside the container the electrodes 3 and 4 are housed, their ends providing the connecting terminals 5 and 6 fixed in the neck portion or mouth 7 of the container. This mouth, after filling the container with the electrolyte, is closed by means of a plug 8 secured in position with a vulcanizable material in order to assure its proper sealing. The plug or closure 8 is provided with a central passage 9 running through the plug lengthwise and terminating outwardly in a small inflatable bag or bulb 10 arranged in folded condition in the chamber or space 11 between the mouth of the container and the flexible cover or cap 12 that is composed of elastic material. The flexible cover 12 is molded of laminar material and conforms perfectly to the shape of the mouth. During manufiacture the pins 13 and 14 are inserted, suitably spaced apart, constituting a plug to be connected to the mains by means of the usual cord or cable, not shown. The elastic tension developed by the major portion of the cover 12 forces the extremities or contact portions 15 and 16 of the connecting pins against the terminals 5 and 6 of the inner electrodes thus establishing the continuity of the electric circuit.

Once the heating device has been connected and alter a short time of about two minutes, the same may be disconnected and used to warm the sheets of a bed or the like. Should the device remain connected to the mains 3 and in case of overheating the steam, the heated air or a mixture of the same surges through the passage 9 inllating the bulb 10 as illustrated in FIG. 2, deforming the elastic cover 12 and causing the interruption of the electric circuit by separating the connectors 5 and 15 and 6 and 16, respectively.

The assembly is completed by two insulating blocks 17 and 18 into which the electrodes 3 and 4 are inserted thus being kept supported and insulated from one an other.

When the device has been disconnected fircm the electric power supply the ions lacking the transfer potential tend to occupy their original positions thus causing the heat to be preserved during a long period of time which in some tests made reached 6 hours.

From the foregoing it is clearly seen that the device of the present invention provides many advantages particularly by its low manuiacturing and operating costs; in addition the invention contemplates the utilization of the device not only for the application shown and dc scribed but also in the maintenance of ambient tempera tures or for industrial uses. On the other hand it evident that modifications of construction and detail miay be made without departing from the scope of the invent-ion which is clearly set forth in the accompanying; claim.

What I claim is:

An electric heater comprising a container, an lelectrolyte disposed in said container and composed of a salt solution at a concentration of at least 6% by weight, a neck portion formed on said container, a plug fitting into said neck portion and defining a passage, a cap surmounting said neck portion and said plug and forming with said plug a closed chamber, two electrodes secured to said plug and each having a terminal extending into said chamber, a collapsible bulb secured in said passage and having one end closed and protruding into said chamber and having its other end open and hitercommunioating with the interior ot' the container, two pins sealed in. said cap and each having a contact portion inside said chamber opposite the respective electrode terminal and protruding with the remainder through the cap to the exterior tor interconnection to an electric source, said cap being composed of elastic material and having its major portion biased normally to be in an active position adjacent said plug so that the contact portions of both pins make electric contact with the electrode terminals, the chamber in the active position of the major cap portion having minimal size, said major cap portion being movable to an inactive position wherein the chamber has maximum size and both pins are out -of-contact with the electrodes thereby disconnecting both electrodes trorn the electric source, said bulb normally being in collapsed state so that the major cap portion due to its bias will be in the active position, said bulb owing to its intercornmunioation with the interior of the container when a predetermined upper temperature limit is surpassed by the electrolyte expanding and pushing the major cap portion from the active to the inactive position.

References Cited in the file of this patent UNITED STATES PATENTS 1,691,749 Williams et al Nov. 13, 1928 1,834,160 ise Dec. 1, 1931 FOREIGN PATENTS 441,584 Italy Nov. 5, 1948 

